General Review an Chapter 1 Flashcards
to review concepts previously covered in Historical and physical geology
What is facies?
A body of sediment with certain characteristics indicative of a depositional environment
How much of earth’s surface is covered in sedimentary rocks?
90 percent
What is the volume of sedimentary rocks in the crust?
less than 10 percent
What are the top 3 most common rocks and what are their percentages?
Shale: 62 percent
Sandstone: 21 percent
Limestone: 13 percent
How are sedimentary rocks classified?
texture and composition
What are the basic sedimentary rock types?
Clastic rocks
Biogenic rocks
Chemical rocks
How are clastic sedimentary rocks formed?
Through the breakdown, transportation, burial, compaction and cementation of previously existing rocks
How are Biogenic sedimentary rocks formed?
Formed directly or indirectly through organic processes.
How are Biogenic rocks classified?
Classified based on chemical composition
Where are biogenic rocks commonly found?
Shallow tropical environments
How are Chemical sedimentary rocks formed?
They are inorganically precipitated from solution, with no transportation and are typically very crystalline.
What are Steno’s 3 principles of geology?
Superposition
Original horizontality
Lateral continuity
What are the types of physical weathering?
Frost
Insolation
Salt
Wetting and drying
Stress release
Exfoliation
What is frost weathering?
Repeated freezing and thawing of water particles in rocks
What is insolation weathering?
Rock surfaces are heated by the sun which creates and thermal gradient within the layers of the rocks. This leads to cracks in the rock surface.
What is wetting and drying?
Drying leads to contraction and absorption of water causes swelling and cracks.
What is stress release weathering?
Rocks deep below the surface are under pressure which is then reduces when the above layers are eroded. This leads to cracks in the rock which are parallel to the topographic surface.
What is exfoliation?
Peeling of the rock surface due to the release of pressure
What are the chemical weathering Processes?
Simple Solution
Hydrolysis
Oxidation
How does simple solution weathering work?
when a mineral dissolves into a solution completely without the precipitation of other minerals.
How does Hydrolysis work?
moving around of H atoms
How does oxidation weathering work?
loss of an electron leads to the formation of oxides or hydroxides
What is the soil formation process?
Addition to ground surface
transformation
Transfers
Removal
bioturbation of soil
How does addition to ground surface work?
Precipitation of dissolved ion of rainwater with solid particles and organic matter from surface vegetation.
How does transformation work?
decomposition of organic matter leads to organic compounds
How does the process of transfer work in soil formation?
movement of solids down from 1 soil horizon to another by groundwater percolation that leads to accumulation of soluble and suspended in the lower horizon.
How does removal work in soil formation?
the removal of substances still in solution to become part of dissolved constituents in groundwater or surface water.
What is the bioturbation of soil?
The disruption of soil by animals
what are the soil horizons
O: surface of organic matter
A: dark colored organic matter that is decaying and mixing with mineral soil
E: less organic matter with fewer iron and aluminum compounds
B: Illuvial concentration of fine organic matter and clay. The original rock has been obliterated by soil forming processes.
C: Partly altered bedrock that is deeply weathered but unaffected by soil forming processes.
What are the most common Paleo-soils?
Quaternary glacial/fluvial soils
occur at unconformities
How to recognize paleo-soils?
Root Traces
Soil horizons
puncated by erosional surface
gradational change in texture, grain size, and color.
Various signs of bioturbation.
What is a karst formation?
one rock that was previously connected that has dissolved apart
What is spherical weathering?
fractures and joints in a rock that cuase the erosion to appear as spheroidal. Also known as exfoliation
What is grust?
coarse decomposed crystalline rock
What is saprolite?
Chemically weathered bedrock in the lower part of soil
How does the type of rock affect weathering rate?
Different minerals weather at different rate
permeable rocks weather faster
How does climate affect weathering rate?
Chemical weathering increases in wet climates with high temperature
Physical weathering increases in cold and arid climates
